INVESTIGADORES
MORENO Silvia Margarita
congresos y reuniones científicas
Título:
Study of the participation of the hinge region of the regulatory subunit in the interaction with the catalytic subunit of fungal cAMP-dependent protein kinases through enzymatic kinetics
Autor/es:
RINALDI, J., OCAMPO, J., ROSSI, S. AND MORENO, S.
Lugar:
Pinamar, Buenos Aires
Reunión:
Congreso; X Congreso internacional de PABMB XLI Reunion Nacional de SAIB; 2005
Institución organizadora:
PABMB y SAIB
Resumen:
There are great differences among species in the affinity between regulatory (R) and catalytic (C) subunits ofPKA. These differences can not be explained by the present structural data. There is a striking sequence. diversity in the hinge region. The aim of this work is to test if the hinge region interacts with C and if it can account for the differences observed among species in the R-C affinity. To approach this issue we have first compared the ability of several peptides to inhibit the phosphorylating activity of Mucor rouxií, Saccharomyces cerevisiae and bovine heart C. The peptide sequences correspond to the autophosphorylation site plus a variable region toward the N-termini of R. We did not observe the competitive inhibition expected, but a dual effect of peptides: they inhibited the phosphorylation as well as they activated it. The whole R had also tiJis dual effect on kemptide phosphorylation.The results are in accordance with idea of an activated holoenzyme. In addition, we compared the kinetic parameters of the peptides phosphorylable version. The results show for the three enzymes that the longer the peptides, the higher were their Vmar andlhe lower their Km' We conclude that the R region studied participates in the interaction and does not account for the differences observed in the R-C affinity among species.